Seamless relocation of a mobile terminal in a wireless network

ABSTRACT

A method for performing seamless relocation of a mobile terminal in a wireless network includes selecting a first serving gateway (SGW) among a plurality of SGWs and a first packet data network gateway (PGW) among a plurality of PGWs, wherein the first SGW connects to the first PGW to setup the first S5 session, establishing a first communication channel between the terminal and the first PGW and assigning an internet protocol (IP) address to the terminal, selecting a second SGW among the plurality of SGWs when the terminal is about to move out of an area being served by the first SGW, connecting the second SGW to the second PGW to setup a new S5 session when a second PGW among the plurality of PGWs is closer to the second SGW than the first PGW or connecting the second SGW to the first PGW to modify the first S5 session when no PGW is closer to the second SGW than the first PGW, establishing a second communication channel between the terminal and the second SGW using the IP address allocated to the terminal, reconfiguring routing for terminal IP destination, and terminating the first communication channel between the terminal and the first PGW.

CROSS REFERENCE TO RELATED APPLICATION

This application claims is a continuation of U.S. application Ser. No.15/018,278 filed Feb. 8, 2016, the entire contents of which are herebyincorporated by reference in its entirety.

TECHNICAL FIELD

Example embodiments generally relate to wireless communications and,more particularly, relate to a method for relocating a terminalseamlessly to a different packet data network gateway (PGW) in awireless network.

BACKGROUND

High speed data communications and the devices that enable suchcommunications have become ubiquitous in modern society. These devicesmake many users capable of maintaining nearly continuous connectivity tothe Internet and other communication networks. Although these high speeddata connections are available through telephone lines, cable modems orother such devices that have a physical wired connection, wirelessconnections have revolutionized our ability to stay connected withoutsacrificing mobility.

However, in spite of the familiarity that people have with remainingcontinuously connected to networks while on the ground, people generallyunderstand that easy and/or cheap connectivity will tend to stop once anaircraft is boarded. Aviation platforms have still not become easily andcheaply connected to communication networks, at least for the passengersonboard. Attempts to stay connected in the air are typically costly andhave bandwidth limitations or high latency problems. Networks willundoubtedly be built to provide passengers with connectivity in the airthat is similar to the connectivity they enjoy on the ground. However,building an air to ground (ATG) network necessarily means that someunique problems will be encountered that are simply not an issue forconventional terrestrial networks. For example, in terrestrial 3GPPstandard networks, at the time a terminal attaches to a network, it willselect a serving cell based on the best available base station. Aspecific serving gateway (SGW) is assigned, generally based on networktopology. The SGW connects to a packet data network gateway (PGW) andthe terminal becomes “homed” and “anchored” to the assigned PGW. Alluser data originating from the terminal or destined for the terminal aretransmitted through the assigned PGW for as long as the terminal remainsattached to the network. The IP address of the terminal is associatedwith that PGW until the terminal detaches from the network.

As the terminal travels across the network, it may handover betweendifferent cells generally based on signal strength. The cell sitehandover may also trigger a handover to a different SGW when theterminal moves out of current SGW service area. However, the PGW towhich the terminal is “homed” and “anchored” does not change. As aresult, end-user data from the terminal to the Internet always departsthe network through the “home” PGW and data destined for the end useralways knows how to “find” the terminal through the terminal'sassociation with the PGW. This works fine for the typical terrestrialnetwork user, who generally stays in a relatively small geographic area.However, when the terminal travels across great geographic distances,the data between the terminal and the assigned PGW will be transmittedback and forth over a long distance, which introduces round-trip latencywith potential negative impact on user-experience. Meanwhile, if theterminal should attempt to change its “homed” PGW and get a new IPaddress during the process, all established connections based on sourceand destination IP addresses between the terminal and its serviceproviders will be disconnected.

BRIEF SUMMARY OF SOME EXAMPLES

Accordingly, some example embodiments may enable seamless relocation ofa terminal to another PGW while maintaining the IP address of theterminal. In one example embodiment, a method for performing seamlessrelocation of a mobile terminal in a wireless network is providedincluding selecting a first serving gateway (SGW) among a plurality ofSGWs and a first packet data network gateway (PGW) among a plurality ofPGWs, wherein the first SGW connects to the first PGW to setup the firstS5 session, establishing a first communication channel between theterminal and the first PGW and assigning an internet protocol (IP)address to the terminal, selecting a second SGW among the plurality ofSGWs when the terminal is about to move out of an area being served bythe first SGW, connecting the second SGW to a second PGW to setup a newS5 session when the second PGW among the plurality of PGWs is closer tothe second SGW than the first PGW or connecting the second SGW to thefirst PGW to modify the first S5 session when no PGW is closer to thesecond SGW than the first PGW, establishing a second communicationchannel between the terminal and the second PGW and maintaining the IPaddress assigned to the terminal previously, reconfiguring routing forterminal IP destination, and terminating the first communication channelbetween the terminal and the first PGW.

The method further includes dynamically configuring routing, by asoftware defined networking (SDN) controller, the IP destination for theterminal through the first PGW, when the first communication channel isestablished, and reconfiguring routing, by the SDN controller, the IPdestination for the terminal through the second PGW when the secondcommunication channel is established.

The method may, in some cases, further include attaching a first defaultbearer to the first communication channel when the first communicationchannel is established between the UE and the first PGW and attaching adedicated bearer to a communication channel in addition to a defaultbearer attached to the communication channel when an additional serviceis required to satisfy a quality of service (QoS) requirement.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S)

Having thus described the invention in general terms, reference will nowbe made to the accompanying drawings, which are not necessarily drawn toscale, and wherein:

FIG. 1 illustrates a functional architecture of the current 3GPPstandards;

FIG. 2 illustrates an exemplary visual representation of communicationchannel between a traveling terminal and a “home” PGW according to thecurrent 3GPP standards;

FIG. 3 illustrates an exemplary functional architecture for seamless PGWrelocation according to an example embodiment;

FIG. 4 is a flow chart to depict an exemplary embodiment for relocatinga terminal to a different PGW while maintaining the assigned IP addressaccording to an example embodiment;

FIG. 5 illustrates an exemplary visual representation of flows of dataand signals among entities of the wireless network according to anexample embodiment;

FIG. 6 illustrates an exemplary visual representation of sequences ofevents and data flows among the entities of the wireless networkaccording to an example embodiment; and

FIG. 7 illustrates a functional block diagram of an apparatus forperforming seamless relocation of a mobile terminal according to anexample embodiment.

DETAILED DESCRIPTION

Some example embodiments now will be described more fully hereinafterwith reference to the accompanying drawings, in which some, but not allexample embodiments are shown. Indeed, the examples described andpictured herein should not be construed as being limiting as to thescope, applicability or configuration of the present disclosure. Rather,these example embodiments are provided so that this disclosure willsatisfy applicable legal requirements. Like reference numerals refer tolike elements throughout. Furthermore, as used herein, the term “or” isto be interpreted as a logical operator that results in true wheneverone or more of its operands are true. As used herein, the terms “data,”“content,” “information” and similar terms may be used interchangeablyto refer to data capable of being transmitted, received and/or stored inaccordance with example embodiments. Thus, use of any such terms shouldnot be taken to limit the spirit and scope of example embodiments.

As used in herein, the terms “component,” “module,” “system,” “device”and the like are intended to include a computer-related entity, such asbut not limited to hardware, firmware, a combination of hardware andsoftware, software, or software in execution. For example, a componentmay be, but is not limited to being, a process running on a processor, aprocessor, an object, an executable, a thread of execution, a program,and/or a computer. By way of example, both an application running on acomputing device and/or the computing device can be a component. One ormore components can reside within a process and/or thread of executionand a component may be localized on one computer and/or distributedbetween two or more computers. In addition, these components can executefrom various computer readable media having various data structuresstored thereon. The components may communicate by way of local and/orremote processes such as in accordance with a signal having one or moredata packets, such as data from one component interacting with anothercomponent in a local system, distributed system, and/or across a networksuch as the Internet with other systems by way of the signal.

The term “terminal” as used herein may be referred to as a mobilestation (MS), user equipment (UE), a user terminal (UT), a wirelessterminal, an access terminal (AT), a terminal, a subscriber unit, asubscriber station (SS), a wireless device, a wireless communicationdevice, a wireless transmit/receive unit (WTRU), a mobile node, amobile, or the other terms. Various embodiments of the terminal mayinclude a cellular phone, a smart phone having a wireless communicationfunction, a personal digital assistant (PDA) having a wirelesscommunication function, a wireless modem, a portable computer having awireless communication function, a capturing device such as a digitalcamera having wireless communication function, a game device having awireless communication function, a music storage and replay appliancehaving a wireless communication function, an Internet appliance enablingwireless Internet access and browsing, and terminals or a portable unithaving combinations of the functions, but example embodiments of thepresent invention are not limited thereto.

The term “base station” as used herein shall be interpreted to mean afixed part for communicating with terminals in a wireless network. Thebase station may indicate the collective name for a node-B, an eNode-B,a base transceiver system, an access point, etc. The base station mayexchange signaling data with a Mobility Management Entity (MME) andsignaling and end-user (bearer) data with the Serving Gateway (SGW).

The term “Mobility Management Entity (MME)” as used herein shall beinterpreted to mean a primary control function for the LTE accessnetwork. The MME serves multiple SGWs and is responsible for selectingthe appropriate PGW when a terminal initially attaches to a network. TheMME is also responsible for selecting a best SGW when the terminalattaches and also during a handover of the terminal to a different cell.

The term “Serving Gateway (SGW)” as used herein serves multiple basestations. It terminates the interface towards the E-UTRAN. There is onlyevery one SGW associated with any terminal at any given point in time.At the time a terminal attaches to the network and during handoverevents, the MME assigns the best SGW (generally based on networktopology) to support that terminal. The SGW functions as the user-planeanchor point for inter-stations handover. The SGW routes end-user(bearer) data to the PGW over the S5 interface.

The term “Packet Data Network Gateway (PGW)” as used herein shall beinterpreted to mean a terminating interface towards the E-UTRAN. The PGWterminates the SGi interface towards an external packet data networks(PDNs). It provides connectivity between a terminal and external PDNs byproviding a single point of entrance and exit for traffic destined foror originating from the terminal. The PGW is selected by the MME at thetime that the terminal attaches to the network. The terminal remainsanchored to the assigned PGW until it detaches from the network or itsDefault Bearer is dropped. The PGW also may be responsible for terminalIP address allocation among its other functional responsibilities.

The term “Home Subscriber Server (HSS)” as used herein shall beinterpreted to mean a central database that contains all user-relateddata and related communication channel information. The HSS supportsterminal authentication and access authorization, session establishmentand mobility management. IP address assignment may be performed by theHSS.

The terms “Software Defined Network (SDN) Controller” and “agent” asused herein shall be interpreted to mean the functional elements, logic,processing, protocols and interfaces to provide flow control and dynamicnetwork configuration, reconfiguration and optimization according tochanging needs of the network and transported traffic (as may bedetermined by traffic volume and flow or performance optimization forexample).

The term “S5/S8 Interface” as used herein shall be interpreted to mean aprimary interface between the SGW and PGW. (S5 and S8 may befunctionally identical; however S8 supports roaming between two/multiplecarriers and is not relevant to this paper.) The S5 interface providesuser plane tunneling and tunnel management between the SGW and PGW. TheS5 interface enables the SGW to connect with multiple PGWs in order toprovide different IP services to the UE (for example a non-collocatedPGW for required PDN connectivity). It also enables SGW re-locationresulting from mobility of a terminal (for example, a handover of theterminal to an eNB supported by a different SGW).

With respect to the term “Bearer—Default Bearer and Dedicated Bearer” asused herein, in LTE standards, bearers carry all data and signalingtraffic. Default Bearers are assigned to a terminal when the terminalattaches to the network. The Default Bearer is assigned an IP addressand remains associated with the terminal for as long as the terminal isattached to the network. All signaling and data traffic employs theDefault Bearer. Where a special handling beyond the scope of the DefaultBearer (usually associated with Quality of Service (QoS) is required,for example Voice over LTE (VoLTE), certain video streaming, etc.) aDedicated Bearer will be assigned to the terminal. The Dedicated Beareremploys the same IP address as the Default Bearer (the Dedicated Bearerbasically piggy backs on the Default Bearer) but provides the specificQoS requirements of the protocol being employed. The Dedicated Bearer isterminated when the special needs IP session ends.

FIG. 1 illustrates a functional architecture of the current 3GPPstandards. Referring to FIG. 1, the diagram provides a high-leveloverview of the functionality relevant to example embodiments and asdefined by 3GPP Enhanced Packet Core (EPC) standards. The diagram showsa functional overview of the 3GPP LTE E-UTRAN (Evolved UniversalTerrestrial Radio Access Networking) making up the radio components ofthe LTE standards and the EPC, which are the signaling and datafunctional components of the LTE standards. The diagram also identifiesthe specific inter-functionality interfaces.

At the time a terminal attaches to the network it will select a servingcell according to a best available base station. During the attachmentprocess, the MME will assign a specific SGW to the terminal. Thisselection is generally based on network topology in that typically aspecific set of eNBs are topologically associated with and supported bythe specific SGW. The MME also assigns a PGW to the terminal. Theterminal becomes “homed” and “anchored” to the assigned PGW. Traffic istunneled between the SGW and the PGW by means of the S5 interface. Alluser data originating from the terminal or destined for the terminalwill exit or enter the network through the assigned PGW for as long asthe terminal remains attached to the network. The IP address of theterminal is associated with that PGW until the terminal detaches fromthe network.

As the terminal travels across the network it may handover betweendifferent base stations generally based on signal strength. If theterminal desires to handover to a base station no longer supported bythe initially assigned SGW, then SGW re-location is orchestrated by theMME and a new SGW is assigned to the terminal. While the SGW is changed,the PGW to which the terminal is “homed” and “anchored” does not change.As a result the S5 interface implements a re-location and user data istunneled between the newly assigned SGW and the same PGW to which theterminal is anchored. As a result, data transmitting from the networkalways depart from the assigned PGW and the data destined for theterminal knows how to “find” the terminal because of its associationwith the specific assigned PGW.

FIG. 2 illustrates an exemplary visual representation of communicationchannel between a traveling terminal and a “home” PGW according to thecurrent 3GPP standards. Current 3GPP LTE standards do not anticipateterminals that require continuous connectivity while traveling acrossgreat geographic distances in comparatively short periods of time. Mostcommon LTE/cellular services are designed for their mobile subscriberswho, in their daily routine, are not traveling very far from the “home”PGW to which their mobile devices are attached. Terminals can movearound and, from time to time, can move out of the coverage area of aparticular SGW coverage and into that of another SGW (SGW re-location),but the terminal remains “homed” to the initially assigned PGW. This mayresult in un-optimized traffic patterns but the occurrence iscomparatively small.

However, there are use cases where the user travels on a high speedtrain or an aircraft. An aircraft using an LTE based Air-to-Ground (ATG)network may travel many hundreds of miles in a matter of hours. Whilethe aircraft transits the country, a user terminal will handover tosuccessive eNBs (cell sites) based on signal strength and will from timeto time be reassigned a nearer SGW. However, the terminal will remain“homed” and “anchored” to the initially assigned PGW. As the distancebetween the terminal and the assigned PGW increases, latency and otherperformance considerations also increases.

For example, in FIG. 2, a terminal on an aircraft departing from NewYork and destined for Los Angeles is initially attached to the nearestand best serving cell based on (among other things) the best signalstrength. An SGW and PGW are assigned the terminal and data traffic istransported to that PGW to which it then becomes “homed” by means of theS5 interface.

As the aircraft travels across the country, the terminal will handoverbetween eNBs (cell-sites) and SGWs as required. In this case, new SGWsare assigned in Missouri and New Mexico before the final SGW at LosAngeles is reached. However, the data traffic between the terminal andthe Internet must go through its “homed” PGW. For each SGW re-location,the S5 tunnel is re-located in order to route the data traffic to the“home” PGW, which results in an un-optimized traffic pattern. Inparticular, even when the SGW is in Missouri, N. Mex. and Los Angeles,data must be transported back to the PGW in New York. Accordingly,incremental round-trip latency is introduced with potential negativeimpact on user-experience.

FIG. 3 illustrates an exemplary functional architecture for seamless PGWrelocation according to an example embodiment. The diagram shows thatstandard 3GPP EPC architecture is integrated with a SDN routingstructure. Referring to FIG. 3, the architecture is capable ofintroducing the following improvements to the standard 3GPP EPCarchitecture. The Seamless PGW Relocation according to an exampleembodiment provides a new MME signaling method to establish a tunnel(e.g., a GPRS Tunneling Protocol (GTP) tunnel) for a connected terminalbetween a new SGW and a new PGW to facilitate terminal PGW attachmentrelocation and employs the SDN as an enabling technology thatreconfigures IP network routing in response to PGW relocation of aterminal, where the same IP address is retained before and after therelocation. Accordingly, the IP address of the terminal for a usersession is unchanged before and after relocation. This is a criticalrequirement in order for a terminal session not to be interrupted duringthe PGW relocation. The end result of the PGW relocation is a moreoptimized traffic pattern using the new PGW and end-user IP sessioncontinuity. Thus, some example embodiments may provide seamless anddynamic reassignment or relocation of the PGW of fast movingcommunications equipment (e.g., an aircraft or other fast platform thatmoves long distances) without any need to change the IP address of suchequipment during one or more transitions of the PGW and SGW.

Referring to FIG. 3, in an example embodiment the capability describedabove can be accomplished by creating a new signaling method and addingan SDN agent onto/in the 3GPP MME 41. The new method on/in the 3GPP MME41 is used to signal a GTP tunnel between SGW 2 and PGW 2 at the timethe MME is facilitating a user terminal handover from Base Station 1 toBase Station 2, in which case the user terminal is served by BaseStation 1, SGW 1, and PGW 1 at the beginning of the handover and servedby Base Station 2, SGW 2, and PGW 2 at the end of handover. The MMEagent 42 may be configured to communicate with a SDN controller 40 toreport terminal PGW attachment relocation events and receive instructionfrom the SDN controller 40 to achieve the seamless and dynamicreassignment or relocation of the PGW as described herein.

Before handover from Base Station 1 to Base Station 2, the terminal 31is served by SGW 1 and PGW 1, and a GTP tunnel for the terminal has beenorchestrated by the MME 41 between SGW 1 and PGW 1. According to 3GPP TS23.401, a S1 or X2 handover with SGW relocation will trigger the MME toorchestrate a GTP tunnel between the new SGW and existing PGW. In orderto facilitate PGW relocation with UE IP address preservation, thefollowing procedure is added to allow the MME to orchestrate a GTPtunnel between the new SGW and target relocation PGW. Here it is assumedthat the MME 41 is both the source MME and the destination MME althoughsource MME and target MME can be different according to 3GPP TS 23.401.To signal GTP between SGW 2 and PGW 2, MME 41 initiates a Create SessionRequest to SGW 2 with PGW 2 as the PGW S5 Address for Control Plane andthe existing UE IP address as the PDN Address Allocation. In reacting toreceiving the Create Session Request from the MME 41, SGW 2 initiates aCreate Session Request to PGW2 with PGW 2 as the PGW S5 Address for theControl Plane and the existing UE IP address as the PDN AddressAllocation. PGW 2 creates data flow for Terminal 31 and Create SessionResponse to SGW 2. SGW 2 will respond to MME 31 with a Create SessionResponse message.

An SDN capable router 38 and 39 may be either built into the PGWfunction or implemented separately as the “next hop” for data traffic.The SDN controller 40 or functionally similar logic may be either builtinto the MME function or implemented separately. When the MME and SDNcontroller are integrated as one component, there is an internalcommunication channel between the MME function and SDN controllerfunction. When the MME and SDN controller are separate functions, theMME has an SDN agent that can communicate with SDN controller through aTCP/IP communication channel. The MME notifies the SDN controller of aPGW relocation event. The terminal IP address is included in thenotification from the MME to the SDN controller. The SDN controller candynamically configure and re-configure routing for SDN routers (ascurrently implemented in SDN routing architectures) to announce thecurrent terminal attachment point in the network.

MME 41 notifies SDN controller 40 of a new PGW relocation eventimmediately after it orchestrates a GTP tunnel between SGW 2 and PGW 2.The SDN controller notifies the success or failure of the routingreconfiguration. If the routing reconfiguration is successful, the MMEdeletes the temporary GTP tunnel between SGW 1 and SGW 2 and theexisting GTP tunnel between SGW 1 and PGW 1. If the routingreconfiguration fails the MME deletes the established GTP tunnel betweenSGW 2 and PGW 2 and temporary GTP tunnel between SGW 1 and SGW 2.

FIG. 4 is a flow chart to depict an exemplary embodiment for relocatinga terminal to a different PGW while maintaining the assigned IP addressaccording to an example embodiment. Referring to FIG. 4, when a terminalattaches to a wireless communication network, a first SGW is selectedamong a plurality of SGWs and a first PGW is selected among a pluralityof PGWs (S400). The first SGW is connected to the first PGW to setup thefirst S5 session. A first communication channel is established betweenthe terminal and the first PGW (S410). An IP address is allocated to theterminal for the communication channel.

When the terminal is about to move out of an area that is being servedby the first SGW, a second SGW is selected generally based on networktopology (S420). If there is a second PGW which is closer to the secondSGW (S430), then the second SGW connects to the second PGW (S450) tosetup a new S5 session. If there is no closer PGW than the first PGW,the second SGW connects to the first PGW (S440) to modify the first S5session. This PGW re-selection logic can be implemented in the MME.

FIG. 5 illustrates exemplary visual representation of flows of data andsignals among entities of the wireless network according to an exampleembodiment. Referring to FIG. 5, there are three major execution phasesin this solution; each phase depends on the result of previous phases.First, the MME orchestrates handover with PGW relocation (or other corecomponents or network elements with the appropriate interfaces andlogic) and notifies the SDN controller of a PGW relocation event, in atimely fashion, with information regarding the terminal that isinvolved, the IP address assigned to the terminal, and the target PGW.Second, the SDN controller instructs the SDN capable router(s) toreconfigure routing for the terminal IP address to deliverreturning-to-terminal traffic to the new PGW. Third, the SDN controllernotifies MME of the success of the routing reconfiguration and the MMEinitiates deletion of the temporary GTP established to assist thehandover and the initial GTP in use before the handover.

Before the SDN controller can reconfigure IP routing to support a PGWrelocation, the SDN controller must know that the relocation hasoccurred and have received at least the following information about theevent: whether the terminal and the IP address that has been relocatedand the source and destination of the PGW. The generation of thisinformation must come from EPC domain and the MME is the logical EPCcomponent to provide this information (or alternatively some elementobtaining the required information from the EPC for use by the SDNcontroller or equivalent logic). Therefore, as indicated in the proposedfunctional architecture, an SDN agent is implemented in the MME tomonitor PGW relocation events and notify the SDN controller when such anevent has happened.

While the MME provides the most logical functional location to trigger aPGW relocation, the relocation logic can be implemented locally in theMME or retrieved from an external management function or orchestrationentity, such as a separate SDN controller or from an external managementor orchestration application at the logical layers above SDN controller.

If the PGW relocation logic is implemented in an SDN controller, the MMEwill query the SDN controller for the optimal PGW in relation to a givenSGW and a given terminal. Once the PGW re-location decision is made bySDN controller (or other applicable logic source), it will utilize thecommunication channel with the SDN agent in the MME to instruct the MMEto trigger a PGW relocation for all existing bearers. During theprocedure, a closer PGW is selected for bearer termination and the sameIP address is attached to the terminal. The completion of the migrationof all bearers associated with a UE is reported back to the SDNcontroller by the SDN agent in the MME.

There is no single design of SDN network that can claim to fit allnetwork scenarios. The general principle of the SDN router setup shouldbe designed to minimize/optimize the SDN controller's effort (reducenetworking complexity, latency, CPU utilization, operational risk)required to reconfigure routing to support PGW relocation. Theconfiguration example presented here proposes all SDN routers be fullymeshed with MPLS LSPs or GRE tunnels so that they can route trafficbetween them in a single hop. In this way, the reconfiguration ofrouting is only needed on these SDN routers, not on any of intermediaterouters between these SDN routers.

Based on the above proposed SDN router setup, the SDN controller canreconfigure routing on the SDN router(s) once it has been informed of aPGW relocation. The reconfiguration synchronizes the host route for theinvolved terminal on all SDN routers pointing to the specific SDN routerthat is directly connected to the new PGW. The net effect of the SDNcontroller is the real time configuration of a host route for theterminal on the SDN routers and utilizing MPLS LSP or GRE tunnels todeliver terminal traffic to the correct PGW. The Internet routers, whichare announcing routes to the Internet at every PGW location, will see nochange during the PGW relocation. They announce the same aggregatedroutes for all terminals

FIG. 6 illustrates exemplary visual representation of sequences ofevents and data flows among the entities of the wireless networkaccording to a seamless PGW relocation caused by a UE handover from asource eNB to a target eNB example embodiment. Referring to FIG. 6, theentities of the wireless network performs the following high levelsteps. In this example representation the source MME and target MME aretreated as the same.

1. For each new terminal attachment request, an SGW and PGW are selectedfor the terminal. The PGW can be collocated with the SGW. FIG. 6represents the existing eNB, SGW, PGW, and first hop router as eNB1,SGW1, PGW1, and Router1

2. Communication sessions between the UE and the Internet (representedas Google web site) are processed at eNB1, SGW1, PGW1, and Router1 foruplink traffic (traffic from the UE to the Internet) and at Router1,PGW1, SGW1, and eNB1 for downlink traffic (traffic from the Internet tothe UE).

3. eNB1 sends an S1 handover request to the MME from eNB1 to eNB2

4. The MME functions as both the source MME and the target MME. The MMEruns gateway selection logic and determines whether or not toorchestrate S1 handover with PGW relocation with SGW2 as the target SGWand PGW2 as the target PGW. The MME signals SGW2 to create a GTP sessionwith PGW2 with the terminal EPS bearer context.

5. SGW2 sends PGW2 a Create Session Request with terminal bearercontext. SGW2 and PGW2 establish the GTP tunnel and PGW2 creates the IPflow based on the same terminal IP addresses.

6. The MME sends eNB2 a Handover Request and eNB2 replies with an MMEhandover response as defined in 3GPP TS 23.401.

7. The MME signals SGW2 to create an indirect tunnel for data forwardingwith SGW1 as described in 3GPP TS 23.401.

8. The MME signals SGW1 to create an indirect tunnel for data forwardingwith SGW2 as described in 3GPP TS 23.401.

9. The MME sends eNB1 a Handover Commend and eNB1 sends a TerminalHandover Commend. The Terminal confirms handover to eNB1, and eNB1notifies the MME of the handover status.

10. eNB2 starts to serve the Terminal and sends a Handover Notificationto the MME.

11. At this point the handover with PGW relocation has been completedbut the routing has not yet converged. The uplink user traffic will gothrough eNB2, SGW2, PGW2, and Router2.

12. The downlink traffic will go through Router1, PGW1, SGW1, SGW2,eNB2. The downlink traffic uses the data forwarding tunnel between SGW1and SGW2.

13. The MME sends SGW2 a Modify Bearer Request as defined in 3GPP TS23.401

14. The MME notifies the SDN controller of a PGW relocation event withRouter1, Router2, and terminal IP address information.

15. The SDN controller performs routing reconfiguration on Router1.

16. The SDN controller performs routing reconfiguration on Router2.

17. The SDN controller notifies MME the completion of the routingreconfiguration.

18. At this point the routing for the Terminal is converged. The uplinkuser traffic will go through eNB2, SGW2, PGW2, and Router2.

19. The downlink user traffic will go through Router2, PGW2, SGW2, andeNB2.

20. Tracking area update.

21. The MME signals SGW1 to delete old session.

21. The MME signals eNB1 to release UE context.

23. The MME signals SGW1 to delete the indirect data forwarding tunnel.

24. The MME signals SGW2 to delete the indirect data forwarding tunnel.

FIG. 7 illustrates a functional block diagram of an apparatus forperforming seamless relocation of a mobile terminal according to anexample embodiment. Referring now to FIG. 7, an apparatus configured forperforming seamless relocation of a mobile terminal is provided. In anexample embodiment, the apparatus may perform the operations describedabove in reference to FIG. 6.

The apparatus may include processing circuitry 70 that is configured toperform data processing, application execution and other processing andmanagement services according to an example embodiment of the presentinvention. In one embodiment, the apparatus may be a mobility managemententity (MME). The processing circuitry 70 may include a processor 71, astorage device 72, and a network interface 73. As such, the processingcircuitry 70 may be embodied as a circuit chip (e.g., an integratedcircuit chip) configured (e.g., with hardware, software or a combinationof hardware and software) to perform operations described herein.However, in some embodiments, the processing circuitry 70 may beembodied as a portion of a server, computer, laptop, workstation or evenone of various mobile computing devices.

The processor 71 may be embodied in a number of different ways. Forexample, the processor 71 may be embodied as various processing meanssuch as a microprocessor or other processing element, a coprocessor, acontroller or various other computing or processing devices includingintegrated circuits such as, for example, an ASIC (application specificintegrated circuit), an FPGA (field programmable gate array), a hardwareaccelerator, or the like. In an example embodiment, the processor 71 maybe configured to execute instructions stored in the storage device 72 orotherwise accessible to the processor 71. As such, whether configured byhardware or software methods, or by a combination thereof, the processor71 may represent an entity (e.g., physically embodied in circuitry)capable of performing operations according to embodiments of the presentinvention while configured accordingly. Thus, for example, when theprocessor 71 is embodied as an ASIC, FPGA or the like, the processor 71may be specifically configured hardware for conducting the operationsdescribed herein. Alternatively, as another example, when the processor71 is embodied as an executor of software instructions, the instructionsmay specifically configure the processor 71 to perform the operationsdescribed herein.

In an example embodiment, the storage device 72 may include one or morenon-transitory storage or memory devices such as, for example, volatileand/or non-volatile memory that may be either fixed or removable. Thestorage device 72 may be configured to store information, data,applications, instructions or the like for enabling the apparatus tocarry out various functions in accordance with example embodiments ofthe present invention. For example, the storage device 72 could beconfigured to buffer input data for processing by the processor 71.Additionally or alternatively, the storage device 72 could be configuredto store instructions for execution by the processor 71. As yet anotheralternative, the storage device 72 may include one of a plurality ofdatabases that may store a variety of files, contents or data sets.Among the contents of the storage device 72, applications may be storedfor execution by the processor 71 in order to carry out thefunctionality associated with each respective application.

The network interface 73 may include one or more interface mechanismsfor enabling communication with other devices and/or networks. In somecases, the network interface 73 may be any means such as a device orcircuitry embodied in either hardware, software, or a combination ofhardware and software that is configured to receive and/or transmit datafrom/to a network and/or any other device or module in communicationwith the processing circuitry 70. In this regard, the network interface73 may include, for example, an antenna (or multiple antennas) andsupporting hardware and/or software for enabling communications with awireless communication network and/or a communication modem or otherhardware/software for supporting communication via cable, digitalsubscriber line (DSL), universal serial bus (USB), Ethernet or othermethods. In situations where the network interface 73 communicates witha network, the network may be any of various examples of wireless orwired communication networks such as, for example, data networks like aLocal Area Network (LAN), a Metropolitan Area Network (MAN), and/or aWide Area Network (WAN), such as the Internet.

Many modifications and other embodiments of the inventions set forthherein will come to mind to one skilled in the art to which theseinventions pertain having the benefit of the teachings presented in theforegoing descriptions and the associated drawings. Therefore, it is tobe understood that the inventions are not to be limited to the specificembodiments disclosed and that modifications and other embodiments areintended to be included within the scope of the appended claims.Moreover, although the foregoing descriptions and the associateddrawings describe exemplary embodiments in the context of certainexemplary combinations of elements and/or functions, it should beappreciated that different combinations of elements and/or functions maybe provided by alternative embodiments without departing from the scopeof the appended claims. In this regard, for example, differentcombinations of elements and/or functions than those explicitlydescribed above are also contemplated as may be set forth in some of theappended claims. In cases where advantages, benefits or solutions toproblems are described herein, it should be appreciated that suchadvantages, benefits and/or solutions may be applicable to some exampleembodiments, but not necessarily all example embodiments. Thus, anyadvantages, benefits or solutions described herein should not be thoughtof as being critical, required or essential to all embodiments or tothat which is claimed herein. Although specific terms are employedherein, they are used in a generic and descriptive sense only and notfor purposes of limitation.

What is claimed is:
 1. A method for performing a seamless relocation ofa terminal in a wireless environment comprises: selecting a firstserving gateway (SGW) among a plurality of SGWs and a first packet datanetwork gateway (PGW) among a plurality of PGWs, wherein the first SGWconnects to the first PGW to setup a first session; establishing a firstcommunication channel between the terminal and the first PGW andassigning an internet protocol (IP) address to the terminal; responsiveto one or more relocations of the terminal to areas served by SGWs otherthan the first SGW, making a location based determination regardingwhether to switch to a second PGW; and maintaining the IP addressassigned to the terminal regardless of whether the switch is made to thesecond PGW when a modification is made to the first session toaccommodate the one or more relocations.
 2. The method of claim 1,wherein maintaining the IP address comprises establishing a secondcommunication channel between the terminal and the second PGW using thesame IP address assigned to the terminal for the first communicationchannel.
 3. The method of claim 1, wherein the location baseddetermination comprises determining whether the second PGW is closer toa second SGW associated with the relocation than the first PGW.
 4. Themethod of claim 3, wherein a mobility management entity (MME) selectsthe first SGW and the second SGW among the plurality of SGWs and selectsthe first PGW and the second PGW among the plurality of PGWs.
 5. Themethod of claim 4, wherein the MME includes a MME agent thatcommunicates with a SDN controller.
 6. The method of claim 4, whereinthe MME notifies the SDN controller of a PGW relocation event when theterminal moves out of the area being served by the first PGW andestablishes a communication channel with the second PGW.
 7. The methodof claim 4, further comprising: dynamically configuring routing ofcontent to the IP address assigned to the terminal previously throughthe first PGW, when the first communication channel is established; andreconfiguring routing of content to the IP address assigned to theterminal previously through the second PGW when the second communicationchannel is established.
 8. The method of claim 1, further comprising:migrating the default bearer attached to the first communication channelwhen the first communication channel is established between the terminaland the first PGW to the default bearer of the second communicationchannel when the second communication channel is established between theterminal and the second PGW.
 9. The method of claim 1, furthercomprising: migrating a dedicated bearer attached to the firstcommunication channel between the terminal and the first PGW to thesecond communication channel between the terminal and the second PGWwhen an additional service is required to satisfy a quality of service(QoS) requirement.
 10. The method of claim 1, wherein the terminalcomprises an airborne terminal and wherein the wireless environmentcomprises an air to ground network.
 11. An apparatus for performing ahand-over of a terminal in a wireless environment, the apparatuscomprising processing circuitry: wherein the processing circuitry isconfigured to: select a first serving gateway (SGW) among a plurality ofSGWs and a first packet data network gateway (PGW) among a plurality ofPGWs, wherein the first SGW connects to the first PGW to setup a firstsession; request the terminal to establish a first communication channelbetween the terminal and the first PGW and assigning an internetprotocol (IP) address to the terminal; responsive to one or morerelocations of the terminal to areas served by SGWs other than the firstSGW, make a location based determination regarding whether to switch toa second PGW; and maintain the IP address assigned to the terminalregardless of whether the switch is made to the second PGW when amodification is made to the first session to accommodate the one or morerelocations.
 12. The apparatus of claim 11, wherein maintaining the IPaddress comprises establishing a second communication channel betweenthe terminal and the second PGW using the same IP address assigned tothe terminal for the first communication channel.
 13. The apparatus ofclaim 11, wherein the location based determination comprises determiningwhether the second PGW is closer to a second SGW associated with therelocation than the first PGW.
 14. The apparatus of claim 13, wherein amobility management entity (MME) selects the first SGW and the secondSGW among the plurality of SGWs and selects the first PGW and the secondPGW among the plurality of PGWs.
 15. The apparatus of claim 14, whereinthe MME includes a MME agent that communicates with a SDN controller.16. The apparatus of claim 14, wherein the MME notifies the SDNcontroller of a PGW relocation event when the terminal moves out of thearea being served by the first PGW and establishes a communicationchannel with the second PGW.
 17. The apparatus of claim 14, furthercomprising: dynamically configuring routing of content to the IP addressassigned to the terminal previously through the first PGW, when thefirst communication channel is established; and reconfiguring routing ofcontent to the IP address assigned to the terminal previously throughthe second PGW when the second communication channel is established. 18.The apparatus of claim 11, wherein the processing circuitry is furtherconfigured to: migrate the default bearer attached to the firstcommunication channel when the first communication channel isestablished between the terminal and the first PGW to the default bearerof the second communication channel when the second communicationchannel is established between the terminal and the second PGW.
 19. Theapparatus of claim 11, wherein the processing circuitry is furtherconfigured to: migrate a dedicated bearer attached to the firstcommunication channel between the terminal and the first PGW to thesecond communication channel between the terminal and the second PGWwhen an additional service is required to satisfy a quality of service(QoS) requirement.
 20. The apparatus of claim 11, wherein the terminalcomprises an airborne terminal and wherein the wireless environmentcomprises an air to ground network.